Guacamole and I did not get off to a good start. We first met in the context of a home-assembly fajita kit – marinated chicken in a little plastic pouch, sachets of sour cream and salsa, a few desiccated tortillas and something distinctly unappetising looking in a small plastic pot. In those innocent pre-pesto and wasabi days, green food was a bit of a novelty outside the salad aisle, and the colour unnerved me until I realised the contents were, in reality, little more than double cream with a soupcon of avocado playing lip service to the original recipe. How exotic I felt, rolling my own dinner.

Now, this was 1994. Leggings and Take That were hot stuff. What puzzles me is why, nearly 20 years later, when both these things have fallen from grace at least twice, the same awful guacamole is still in fashion. It's not as if Mexican food is a novelty; why, these days you can even find restaurants that manage to make money without the help of a hat stand laden with amusing headgear and 15 types of tequila slammer. But somehow, the pea green sludge, heavy with dairy and low on flavour, still lurks alongside the hummus and the taramasalata in the chilled aisle.

As I discovered some years later, guacamole should be zingy and fresh tasting, to cut through the creamy richness of the ripe avocado. Rick Bayless, one of the finest Mexican chefs north of the Rio Grande, and an award-winning writer on the subject, describes it in his Mexican Kitchen cookbook as "a verdant, thick-textured bowl of festivity, ripe with the elusive flavour of avocado. Mash in a little lime, raw onion, coriander, chilli, perhaps tomato, and the avocado comes fully alive."

According to Bon Appetit magazine, down Mexico way, "some cooks coarsely mash avocados, season them with salt – maybe a little garlic – and call the result 'guacamole.'" Their point, I think, is that there is no definitive recipe, which means I won't have to worry too much about "authenticity", although I probably won't go as far as the Las Vegas restaurant that encouraged me to add lobster and mango as part of their guacamole masterclass.

The allium affair

Now, forgive me for boasting, but I'm kind of a big deal in the guacamole world – among my friends at least. I've had people threaten to pull out of parties if the customary 25-avocado bucket of the stuff isn't putting in an appearance, although that could be a reflection of the quality of the rest of the festivities I suppose. Anyway, I never put onions in. Ever. But many people, it seems, disagree.

Rick Bayless adds half a finely diced white onion to 3 mashed avocados, 2 diced tomatoes, 2 finely chopped green chillies, and 3 tbsp chopped coriander, and seasons with salt, pepper, and 2–3 tbsp lime juice. Thomasina Miers of Mexican restaurant chain Wahaca advocates red onion instead, and Bon Appetit raises the issue of garlic: following advice online, I opt for 1 finely minced clove. Having read the relevant entry in Alan Davidson's indispensable Oxford Companion to Food, which informs me that the Aztecs would have used "New World onions", I decide to give spring onions a try as well, as these seem most similar to the wild onions native to north America.

Sadly I'm unable to get hold of a white onion, which seem to be strangely few and far between in my neck of the woods, so I substitute a pale yellow version instead. Although I quite like the sweetness of the red onion, I find the flavour of both this and the yellow one a bit too acrid for the delicate avocado – and as for the garlic, well, it's utterly overpowering, and jars with the rest of the ingredients. The spring onions are more of a success – cleaner and greener tasting, they add a slight onion heat without muddying the rest of the flavours. I suspect they may well be closer to the large white onion than the yellow varieties we get here.

Tomatoes

A selection of guacamole ingredients. Photograph: Felicity Cloake

Oddly enough, tomatoes seem to be considered an optional extra in guacamole: Thomasina Miers doesn't include them, and opinion online is divided. I do try one without, but it seems sadly one-dimensional without their acidic fruitiness. I also test a Rick Bayless variation published online for an Obama victory party (Michelle O was apparently a big fan of the guacamole at his Chicago restaurant, Topolobampo) using sun-dried tomatoes. They're good, but I prefer the sharper taste of the fresh variety. Still, it's a good substitute to bear in mind for the long months ahead, when our tomatoes will be watery and thin on flavour.

Chillies

Fresh green chillies seem to be the consensus here – serrano or jalapeño – but I'm curious to know how dried chillies would fare in a last-minute guacamole emergency. I try shaking in some red chilli flakes, which produce an acceptable, but rather fiery result, and adding a smoked chipotle chilli in a spicy adobo sauce, following a suggestion from Mexican chef Pati Jinich's blog.

The latter goes down very well with one of my testers, and not so well with the other, who describes it as "like bacon". (Apparently this is not a good thing in a guacamole; personally I'm not so sure.) Although the fresher flavour of the green chillies works better with the rest of the ingredients, this is certainly a variation I'd consider trying again in future, particularly if I was serving the guacamole with meat.

Dairy

Despite my antipathy towards supermarket versions, I'm forced to concede, after a little research, that adding sour cream to guacamole is quite usual in some Mexican regions. Online adherents, predominantly American, claim it adds a quite incredibly rich texture to the end result. I find it makes it bland, and heavy. If you want crema with my guac, add it yourself while I'm not looking.

Coriander and lime

Coriander, aka cilantro. Photograph: Felicity Cloake

Also questionable, according to some sources, but I couldn't imagine guacamole without either of them, and my experiments prove me right. The lime adds zing, and the coriander an aromatic quality which brings depth to the bright flavours of the other ingredients.

Method

There's a lot of talk online about molcajete, the traditional Mexican mortar, made out of basalt. People attribute mystical qualities to this ancient piece of equipment, even down to claiming that the minerals of the rock itself, part of mother Mexico, imbue the guacamole with a particularly "authentic" flavour.

Sadly, I have only an ordinary stone mortar at my disposal, but obediently I grind together a teaspoon each of chopped chilli, spring onion and coriander to make a paste, and then gently mash in the cubes of avocado, being sure to leave some chunks intact. I then fold in the chopped tomato, and the rest of the chilli, coriander and spring onion, and sprinkle with lime juice and salt. Although I can't detect much difference in texture, the paste has combined better with the avocados, which gives the guacamole a more harmoniously spicy, well-rounded flavour.

Keeping it green

Ashamed as I am to admit this, I'd long believed that popping an avocado stone into the guacamole helped to delay discolouration. I'd even passed this cunning trick on to others. And now revered food writer Harold McGee has burst my bubble by claiming the only purpose the stone serves is to keep oxygen away from the guacamole beneath it – "there doesn't seem to be anything special about the pit" he concludes, after experimenting with a lightbulb of a similar shape and size. The only thing that slows down the browning process, he says, is excluding the air from it, which means pressing cling film on to the surface.

Methods of keeping guacamole green - left to right, clingfilm on surface, clingfilm on top, stone in and open. Photograph: Felicity Cloake

McGee recommends Saran Wrap, made from something called PVdC, which does not appear to be widely available in this country, so I have to make do with ordinary supermarket stuff. I divide a batch of my final recipe between four bowls, and leave one open to the air, add a stone to the next, cover one with clingfilm, and press clingfilm on to the surface of the last. Two hours later, I take them out of the fridge, hoping to prove McGee wrong.

I don't, of course. Running from fresh green to sludge brown, we have the guacamole with the clingfilmed surface, which barely seems to have changed colour, the one with the cling film over the top of the bowl, which has visibly discoloured, the one with the stone, which is green underneath the object and elsewhere exactly the same colour as the open bowl: murky.

Guacamole is one of those dishes which is happy to be played around with according to taste. The only golden rule is – use ripe avocados!

1. Put a teaspoon each of the chilli, onion and coriander into a pestle and mortar, along with a pinch of coarse salt, and grind to a paste.

2. Peel the avocados and remove the stone. Cut into cubes, then mash into a chunky paste, leaving some pieces intact.

3. Stir the chilli paste into the avocado, and then gently fold in the tomatoes and the rest of the onions, chilli and coriander. Add lime juice and salt to taste. Serve immediately, or cover the surface with cling film and refrigerate.

What's your perfect guacamole recipe – is the avocado the only sacred ingredient, or would you fight like an Aztec warrior king for onions, coriander, or tomato? Do you prefer it chunky or smooth, is a molcajete worth the money; and has anyone found a good ready-made version?